CHAPTER 2
Literature Review

This chapter presents the findings of the literature review conducted to support and inform this synthesis study and provides an overview of existing publications and guidance on ramp operations, safety, and management. Recent studies are included as well as material from earlier works that remain relevant and continue to provide insights into airport ramp safety. The purpose of this literature review was to (1) establish an understanding of the current state of practice, (2) identify themes, and (3) highlight areas where knowledge is limited or evolving.

Key sources include past ACRP reports and studies relevant to ramp operations and safety, FAA materials [e.g., ACs, policy documents, and online resources and regulations such as Code of Federal Regulations (CFR) Title 14, Part 121]. These sources offer information about the regulatory context and practical guidance influencing safety practices in the field. The literature reviewed also included academic articles, industry publications, and technical papers addressing relevant topics such as the following:

• Current and emerging ramp safety practices;
• Recommended safety strategies and operational procedures;
• Human factors considerations affecting ground operations and personnel safety;
• Performance measures and metrics used to monitor and improve ramp safety outcomes; and
• SMS frameworks, tools, and guidance as they apply to ramp environments.

These sources provide a well-rounded perspective on the existing knowledge and help frame the subsequent analysis of survey and case example findings in later chapters.

Current Regulations

As mentioned earlier, this part of the literature review presents key regulations and ACs that establish the safety and operational framework for airport ramp environments. These documents (1) clarify the regulatory context in which airports, airlines, and GSPs operate and (2) directly inform the focus areas of this synthesis on training, risk management, and safety practices.

Airline Regulations

• CFR Title 14, Part 121, “Operating Requirements: Domestic, Flag and Supplemental Operations” (ECFR 14 CFR Part 121) mandates that all airlines and GSPs implement comprehensive safety and operational training for their personnel. Required training topics include ramp safety, handling of dangerous goods, jet blast and suction awareness, and services for passengers with disabilities. These requirements aim to ensure consistent baseline safety awareness and competency among all staff who operate in ramp areas.

• AC 00-34B Aircraft Ground Handling, Servicing, and Marshalling (FAA 2024) addresses ground handling, servicing, and marshalling operations and reinforces the importance of a structured safety management approach, with managers and supervisors being responsible for identifying, mitigating, and documenting hazards to reduce uncertainty and risk in decision-making. AC 00-34B outlines risk control measures, such as engineering solutions, procedural or administrative controls, and the use of personal protective equipment (PPE). This AC also stresses the importance of education, formal training, and on-the-job training. Staff can use AC 00-34B in implementing safety practices and enforcing them on the ramp. AC 00-34B also provides information on the roles of training and human factors in ramp safety programs. This topic is also covered in the International Air Transportation Association (IATA) Ground Operations Manual (IATA 2021) and in the FAA Guide to Ground Vehicle Operations (FAA 2020).

Airport Regulations

• AC 150/5200-37A Safety Management Systems for Airports (FAA 2023b) provides detailed guidance on implementing SMS at airports. The AC defines the four core SMS components (i.e., safety policy, safety risk management, safety assurance, and safety promotion) and offers practical strategies for identifying and mitigating hazards in airside environments. For ACRP Synthesis 143, the relevance of AC 150/5200-37A lies in its emphasis on proactive risk identification and organizational safety culture, both of which are critical to understanding how ramp safety is managed at different airports.
• AC 120-57C Low Visibility Operations/Surface Movement Guidance and Control Systems (LVO/SMGCS) (FAA 2023a) focuses on surface movement guidance and control systems (SMGCS) and surface movement surveillance systems (SMSS). AC 120-57C suggests that airports establish SMGCS plans for operations conducted in low-visibility conditions (i.e., runway visual range below 1,200 feet). While primarily focusing on movement areas AC 120-57C includes ramp area consideration in several sections. The AC assigns responsibility to airport operators for ensuring that ground vehicle operators receive appropriate training during these conditions. The AC also clarifies the division of roles: while air traffic controllers oversee the operation of stop bar lighting systems, airport tenants are responsible for correcting deficiencies that do not comply with the SMGCS. AC 120-57C is especially relevant for understanding how responsibilities are distributed among different ramp users.
• AC 150/5370-2G Operational Safety on Airports During Construction (FAA 2017) provides guidelines for operational safety at airports during construction and is directly relevant to ramp areas, given that construction in these zones poses significant operational and safety risks due to the high density of aircraft movements, GSE, and personnel. The AC suggests airports incorporate ramp safety considerations into their Construction Safety Phasing Plan, addressing issues such as maintaining clear taxi routes, preventing jet blast and prop wash hazards, controlling access of construction vehicles, ensuring proper barricades and lighting, and minimizing FOD. By emphasizing hazard mitigation, coordination with tenants, and clear communication procedures, the AC ensures that construction near ramps does not disrupt ground operations or compromise safety for aircraft, crews, and ramp workers.
• AC 150/5210-18A Systems for Interactive Training of Airport Personnel (FAA 2015) provides guidance on the design and use of interactive training systems for airport personnel, with the intent of supporting compliance with federally mandated safety and security requirements. Although the FAA does not mandate the use of this AC for all airports, its application is required for any project funded through the AIP or the PFC Program, in accordance with Grant Assurance No. 34 and PFC Assurance No. 9. The AC outlines standards for the acquisition and implementation of training equipment and software.

• AC 150/5200 (Section 2.8) highlights the federal emphasis on standardized training to enhance ramp safety. Interactive training systems are a key component of safety culture and workforce preparedness, both of which are critical areas of focus in this studyʼs examination of current ramp safety practices.

Ramp Safety Practices

• ACRP Synthesis 29: Ramp Safety Practices (Landry and Ingolia 2011) provided a snapshot of current ramp area operations and safety in the United States, highlighting the complexity and inherent risks of ramp environments across airports of all sizes. ACRP Synthesis 29 found that no national standards exist for non-movement area markings, ground operations, or training, and there is no centralized data system to track accident causes or safety trends. Airlines and GSPs often develop their own training programs to meet regulatory requirements, and safety roles vary depending on airport agreements. This synthesis builds on these findings by addressing existing gaps through a national survey and case examples and taking a deeper focus on human factors such as fatigue and frequency of training. Unlike ACRP Synthesis 29, this synthesis explores how performance is assessed and communicated and offers updated analysis based on more survey data and operational insights.
• ACRP Report 62: Airport Apron Management and Control Programs (Ricondo & Associates Inc., et al. 2012) documents airport apron management and control programs conducted during site visits to U.S. and international airports. The results of the interviews revealed that apron safety is a top priority for airports, airlines, and ground handlers. This priority is driven by the high cost of injuries, equipment damage, and operational disruptions. Despite the lack of formal regulation in non-movement areas, organizations consistently invest in training, procedures, and communication protocols to prevent incidents. ACRP Report 62 notes growing interest in applying SMS to apron areas, as proposed in recent FAA rulemaking. Although existing tools like airport certification manuals and FAA guidance support safety efforts, the lack of a centralized data system limits ability to objectively assess safety performance. Formal apron management programs could enhance standardization and data collection, although implementation must consider the unique operational flexibility of U.S. airports (Ricondo & Associates Inc., et al. 2012).
• Inan and Orhan (Inan and Orhan 2021) used the Analytic Hierarchy Process (AHP) to assess key human factors contributing to ramp accidents and offered a structured, quantifiable approach to evaluating complex operational risks. The results showed that fatigue in led human factors, accounting for 70% of ramp-related incidents. Overconfidence followed at 17%, while inattention accounted for 11%. Among communication-based issues, incorrect marshaling signals were identified as the most common cause, followed by lack of communication, and work shift misalignment.

  In terms of physical risks, kneeling and bending were rated as the most hazardous movements. This was followed by overtime work, and repetitive tasks. From an environmental perspective, bad weather posed the highest risk (45%), particularly for workers exposed to extreme heat or cold. Noise exposure (31%) and low visibility (22%) were also significant contributors.

  The AHP study reinforces findings from other literature focused on human factors in ramp safety, such as the role of fatigue and environmental stressors. However, the AHP study differs in its method of approach by applying AHP to prioritize risk factors, providing a practical tool for identifying and addressing safety issues. Compared with previous studies that focused more on observational analysis or narrative case studies, this research adds a data-driven decision-making model that can help airport and airline operators systematically target the most critical areas of concern.

• A report from the United States Government Accountability Office (USGAO 2007) highlights both progress and persistent challenges in improving runway and ramp safety in the U.S. aviation system. While the FAA has implemented most of its 2002 runway safety initiatives, including enhanced airport markings, lighting, and pilot/controller training, the overall rate of runway incursions began to rise again by 2007, nearing early 2000s peak levels. A lack of coordination, outdated safety plans, technological delays, and data deficiencies have hindered further progress. Air traffic controller fatigue, exacerbated by frequent overtime and 6-day work weeks, remains a concern, with experts calling for improved fatigue management and a nonpunitive reporting system for safety concerns.

  In terms of ramp safety, the USGAO report found no complete or centralized data on nonfatal injuries or incident trends, making it difficult to assess risks or evaluate the effectiveness of mitigation strategies. There are also no federal or industrywide standards for ground handling operations, leaving oversight to individual airlines and airports. Although some airlines and organizations have initiated proactive safety efforts (e.g., setting safety targets or using ramp towers), expert opinion suggests that promoting a strong safety culture would have the greatest potential for reducing ramp incidents. The report suggests several measures, including updating the runway safety plan, improving data collection, and directly addressing controller fatigue.

  The USGAO report reinforces earlier findings about the role of human factors, especially fatigue, in ramp and runway safety that aligns with recent literature focused on fatigue management systems for ramp workers. The report also echoes prior studies noting fragmented oversight and the absence of standardization in ramp safety procedures. However, it differs in its broader system-level focus, addressing both technological infrastructure and institutional barriers, such as interagency coordination and leadership accountability, rather than focusing only on ground personnel behavior or human error typologies. Unlike studies that use qualitative thematic analysis or AHP to prioritize risk factors, this report integrates stakeholder interviews, survey data, and institutional audit findings to shape its recommendations.

Human Factors in Ramp Safety

• Muecklich et al. (Muecklich et al. 2023) reviewed 87 accident and incident reports from the National Transportation Safety Board, the Australian Transport Safety Bureau, and the German Federal Bureau of Aircraft Accident Investigation from 2000 to 2020, applying both the “Human Factors Dirty Dozen” model (FAA 2012) and the “Human Factors Analysis and Classification Scheme” to conduct a systematic and thematic analysis of the reports. The studyʼs findings reveal that lack of situational awareness and failure to follow standard procedures were the primary factors behind these accidents. These human factors failures are particularly concerning in ramp environments, where operations are often fast paced, involve multiple stakeholders, and require close coordination between management and personnel.
• The study identified aircraft pushback and towing, aircraft arrival and departure, and aircraft weight and balance as the operational areas most critical to safety. Although these activities are routine, they are also high-risk components of ramp operations, thus explaining the need for well-structured training, communication, and procedural compliance between management and operators as emphasized throughout the ACs. The Muecklich study on ground operations offers an important contrast to the regulatory and advisory materials reviewed earlier in this synthesis.
• The areas critical to safety found in Muecklich are reinforced by the Global Aviation Study (Allianz 2025), in which the researchers concluded that most ramp incidents occurred in high-congestion areas, with 43% happening within the gate stop area, 39% at the gate entry/exit, and 18% in the ramp fringe near taxiways. Incidents were more common during arrivals, particularly

• in the gate stop area. Furthermore, ground equipment and personnel were especially vulnerable, with 21% of incidents occurring after aircraft were stopped. Although ground guidance was provided in 64% of cases and communication was attempted in 79%, over half of the reports cited poor communication. Contributing factors to these incidents included ramp congestion, increased flight volume, and the mismatch between aircraft size and gate design.
• Marquardt et al. (Marquardt et al. 2024) examines human error in complex sociotechnical systems, where people and technology interact in safety-critical environments. Using data from 544 workers across seven process industries, the research identifies a three-factor model of error causation based on the Dirty Dozen framework. The study introduces an adaptive error management system that provides evidence-based interventions to manage and reduce human errors. This publication also highlights the importance of organizational resilience, learning from mistakes, and fostering a strong safety culture to handle unexpected challenges in sociotechnical systems effectively.
• Morais et al. (Morais et al. 2023) took a more direct approach in addressing the human factors issue by specifically focusing on contributing factors in accidents. This study highlights fatigue as a critical and often overlooked human factors in ground handling safety. Despite advancements in technical systems, human error, particularly due to fatigue, remains a major contributor to incidents among ramp workers. The constant demands for 24/7 operations, irregular shifts, time pressure, and insufficient rest were found to significantly affect worker performance and alertness.

  The Morais study proposes the development of a fatigue management system (FMS) specifically for ramp workers. This system would include layered defenses such as education, training, optimized scheduling, rest breaks, recovery sleep, and voluntary fatigue reporting. The findings suggest that, although implementing an FMS would require substantial effort, such a system could meaningfully improve both safety and worker well-being.

  Compared to previous studies that used models like the Human Factors Analysis and Classification System and the Dirty Dozen to identify broad categories of human error (e.g., lack of situational awareness, procedural noncompliance), the Morais research goes a step further by isolating fatigue as a root cause and offering a targeted mitigation strategy. The Morais study adds depth to the literature by addressing the “why” behind human performance issues and reinforces the need for systemic solutions that include physiological and organizational considerations in ramp safety.